In recent years, users of information processing devices have increasingly widely used portable terminal devices such as portable telephones and personal digital assistants (PDAs), and various content could thus be acquired and used in these portable terminal devices.
In these portable terminal devices, information input units such as a keyboard, a rotary type operating element (jog dial), and a touch panel which is a contact type information input unit are generally installed as hardware.
In the information input unit using the touch panel or the like, information corresponding to a contact position is transmitted to a central processing unit (CPU) of the portable terminal device to perform a predetermined operation by using one's finger or a dedicated input pen to contact a screen on which a specific image such as an icon is displayed and inputting position information of the contact position.
In the contact type information input unit such as the touch panel, a resistance film type, an electrostatic capacitance type or the like is used.
Between these, the contact type information input unit of the electrostatic capacitance type can be widely adopted as the information input unit because a thickness of a device main body can be thinly formed and a degree of freedom of a shape of the panel itself is also high.
As well-known technology in this art, for example, in Patent Document 1, technology for generating a plurality of types of vibrations, each of which has a vibration time differing according to each operator corresponding to a sliding speed or a sliding operation time of one's finger or the like of the operator, is disclosed. Specifically, there are provided an input detection means which has an input detection surface and detects a contact position of the finger of the operator and a sliding speed of the finger of the operator, a CPU which calculates a vibration pattern based on the sliding speed detected by the input detection means, and a vibration means which vibrates the input detection surface based on the vibration pattern calculated by the CPU. According to a distance from a position at which the finger of the operator is in contact with the input detection surface, the CPU calculates the vibration pattern to generate vibrations from low-frequency and small-amplitude vibration to high-frequency and large-amplitude vibration. According to this configuration, it is possible to generate a plurality of types of vibrations, each of which has a vibration pattern differing according to each operator corresponding to a sliding speed or a sliding operation time of an operator's finger.
In Patent Document 1, a digital camera having an electrostatic capacitance type touch panel for a sliding input on an upper surface plate of a camera main body is disclosed.
The user can perform an operation such as zoom-in, zoom-out, reproduction/fast forward/rewind, focus adjustment, or volume adjustment by causing an operation body such as one's finger to slide in a predetermined direction in a state in which the operation body such as the finger is in contact with an electrostatic capacitance type input sheet.
Here, the principle of the above-described electrostatic capacitance type information input device will be described.
FIG. 5 is an explanatory diagram illustrating the principle of an electrostatic capacitance type sensor.
As illustrated in FIG. 5, if one's finger 11 is in proximity (contact) with the touch panel 13 as illustrated in FIG. 6A or 6B when the user operates the touch panel 13, electrostatic capacitance is generated between the touch panel 13 and the user's finger 11. This is because a human body has conductivity.
The electrostatic capacitance generated between the touch panel 13 and the user's finger 11 has displacement in inverse proportion to a distance between the touch panel and the user's finger as illustrated in Equation (1).
In Equation (1), C is a reference sign denoting electrostatic capacitance, c is a reference sign denoting a dielectric constant of each material, S is a reference sign denoting an area of the finger 11, and D is a reference sign denoting a distance between the finger 11 and the touch panel 13.C=(∈·S)/D  (1)
An input device performs a predetermined process input according to the user's touch operation by detecting position information based on electrostatic capacitance generated when the user brings the finger 11 in contact with the touch panel 13.
FIGS. 7A and 7B are diagrams illustrating input sensitivity information (variation amounts in electrostatic capacitance) in a bare hand state and a gloved state as illustrated in FIGS. 6A and 6B.
In a threshold value of a normal sensitivity mode illustrated in FIG. 7A, as in the case of the bare hand illustrated in FIG. 6A, no touch detection is performed when the input sensitivity information does not exceed a normal sensitivity threshold value. In addition, in the high-sensitivity mode, because the touch detection is performed when the input sensitivity information exceeds the threshold value of the high-sensitivity mode, the touch detection is performed even with the bare hand illustrated in FIG. 6A and even in the case of the glove illustrated in FIG. 6B.
In addition, for example, in Patent Document 2, technology for adjusting the sensitivity of the input detection unit according to an operation environment of the user is disclosed. Specifically, the CPU determines whether to adjust an output level of a position signal output from an input detection unit based on sensitivity information (sensitivity data) detected by the sensitivity detection unit. When it is determined that a value of the sensitivity data is less than the threshold value (gloved), the input detection unit is set to high sensitivity based on adjustment data supplied from the CPU. On the other hand, when it is determined that the value of the sensitivity data is less than the threshold value (ungloved), the input detection unit is maintained at standard sensitivity based on the adjustment data supplied from the CPU or the input detection unit is changed from a high-sensitivity setting to standard (low) sensitivity. Thereby, because it is possible to optimally set the sensitivity of the input detection unit according to an operation environment such as when the user wears a glove or when the user does not wear a glove, information can be accurately input and an erroneous operation can be prevented.
Further, for example, in Patent Document 3, a threshold value correction device provided to automatically correct a threshold value of an in-vehicle device is disclosed. Specifically, a driver's finger touches a push start switch for starting and stopping an engine and therefore the presence/absence of detection of an electrostatic capacitance sensor within the push start switch is determined, electrostatic capacitance of the electrostatic capacitance sensor is calculated by a microcomputer, and the threshold value is corrected based on the electrostatic capacitance. Further, the microcomputer sets the corrected threshold value in an in-vehicle device such as an air conditioner or an audio device having the electrostatic capacitance sensor.